Research On Electro-optic Modulator Of Integrated Vertical Coupling Structure

Hybrid integrated of electricity-optics-electricity is the development of chip. MEMSintegrated chip constitute optoelectronic integrated system with practical value. Takes fulladvantage of high-density integrated photonic devices operating in parallel andhigh-speed optical input/output capability, skillfully combined with the photon functionsand electronic functions, constitute a high-speed and large scale integrated systems withtransmit, modulation, detection optical signal and amplify, logical, intelligent controlelectrical signals. It has great significance and broad prospect in optical interconnects,optical switching, optical information processing. Micro-ring resonator integrated systemwhich fabricated on silicon-on-insulator (SOI) gradually attracted widespread attentionfrom domestic and international scholars.This dissertation based on the latest international achievements as guidelines, forhigh-Q optical micro-ring resonator chip integrated system carried out a study ofsilicon-based optical waveguide several discrete devices, which is mainly around thewaveguide electro-optic modulator including the grating couplers, ring resonators andet.al. The main contents are summarized in the following aspects:(1) Theory and design: Grating coupler and ring resonator look as coupling unit andsensitive unit of electro-optic modulator respectively and do the thorough research onthese basic theories. Grating coupler and ring resonator are simulated about groove depthof grating, period, the angle of incidence by optical simulation software FDTD.Meanwhile, key parameters of waveguide width, bend radius and the gap betweenwaveguide and resonator are investigated. A novel four-ring cascade structure is designed.Resonance peaks split can be realized. Simulation analysis of the electro-optic effect andthe frequency modulation is performed by simulation software Sentaurus TCAD todetermine the final modulator parameters of structures and technics.(2)Preparation process: The preparation of grating coupler and ring resonator isfabricated with electron beam lithography and inductively coupled plasma etchingprocess. According to the design of the doping concentration and doping depth, the modulator is used of ion implantation to complete the preparation of electro-opticmodulator PIN diode, and the final structure of the modulator was prepared after a seriesof PCB versions connecting.(3)Testing: compared with the experiments of end-face coupling and verticalcoupling, the result indicate that the coupling efficiency of end-face coupling method isaround12%,while the coupling efficiency of grating coupler with antireflective coating isaround26%. The encapsulation experiment of fiber-grating is carried out, and theefficiency and stability of the device is improved considerably. In terms of characteristicsof resonator, four-ring structure not only obtains a high quality factor with72,000, opticaldelay but also can achieve a nice temperature sensitivity0.16nm/℃. The testing platformfor modulator after verifying a better performance of optical coupler and a sensitive unitis set up. Static and dynamic characteristics of the modulator are tested, respectively. Theshift of the resonance peak in spectral curve is achieved by experiments. The stableoutput signal of30MHz is achieved in dynamics tests.